I think Guelzo's insight, that Protestantism, especially its more fundamentalist wing, was severely challenged by Lyell on geology is key. Edmund Gosse, recounting the crisis as it struck his father, mentions Lyell but Darwin far less, if at all -- the scientific basis for "old earth" appears to have been an earlier, and possibly stronger, challenge to Biblical literalism. By the time of The Origin of Species in 1859, the loss of influence by the evangelical wing of TEC was well under way.
By the same token, railroads, as a very visible early manifestation of technology, appeared in the US and the UK at roughly the same time in the 1830s, and in demonstrating the superiority of materialist technology -- and let's not forget, raising relative living standards, as all subsequent industrial technology would do -- undermined the traditional unworldly claims of religion. I've said before that the simultaneous successes of rail technology and the Oxford Movement aren't a coincidence.
My own somewhat idiosyncratic view is that William James's 1902 The Varieties of Religious Experience was the first effective response to Hume, Lyell, and Darwin, at least by American Protestants, to this development, arguing that the hope of heaven was not the only solution that traditional religion offered to the human condition. The religious impulse is built into human nature, and it is meant to address problems beyond simple poverty and disease. Aquinas, of course, would not disagree.
But James was too late for the REC. I agree with Guelzo that the swift rise and dominance of the Anglo-Catholic faction in TEC reflected a shift in social class orientation, whereby Jacksonian primitive republicans were abandoned in favor of new elites made wealthy by industrial technology. The new style was friendly to wealth and ostentation, although Guelzo is also correct in saying it proved a distraction, not an answer, to the fundamental questions posed by the rising tide in living standards that lifted all boats, combined with the materialist threats to spirituality.
I think there are many similarities to the 1873 REC break and the "continuing" movement a century later. The biggest is that in both cases, as Douglas Bess pointed out with the "continuers", TEC took no notice. The REC had no focus beyond a certain class-based resentment against the TEC majority, and it quickly subdivided into its own conflicts over liturgy and vestments. The "continuers" have fared no differently, with the original ACC splitting over personalities and the other splinter groups oriented mainly toward personal agendas and almost cult-like followings.
By the 21st century, both the REC and the "continuers" have sought to join larger groups, with the remnant REC going into the ACNA and presumably accepting the 1979 BCP, which would have been anathema to Cummins and Cheney, while four of the biggest "continuing" groups are now proposing some type of merger with the PNCC. It's worth pointing out that if this were to take place, the numbers involved would be some multiple of the membership of the OCSP, which has not made a significant dent in the "continuing" movement.
This brings me to my question here: what problem was the REC trying to solve? I would guess that a major part of the REC's failure was that it never clearly defined what the problem was -- Cummins and his allies apparently resented the success of the Anglo-Catholic movement, but resentment isn't a program. On the other hand, the real problem, the one Guelzo identifies posed by Hume, Lyell, and Darwin, went far beyond preferences in liturgy and vestments but doesn't seem to have been clearly identified by either side.
Anglicanorum coetibus is rather plainly trying to appeal to the resentment wing of Anglicanism. Resentment is not a program, and it isn't a selling point.
